The Republican businessman ran a campaign which drew heavily on self-deprecating shtick and toxic TV ads, both of which portrayed him as plain-talking and uncomplicated. Not fancy and elegant like his Democratic opponent, Harold Ford, the bachelor offspring of a political dynasty and Washington prep school.

Corker bucked the anti-Republican trend last week with help from a political code born out of a culture war that still echoes through American political discourse: a language that pits 'them' against 'us': 'Hollywood', 'San Francisco' and 'Washington' scheming against the values of the heartland.

Corker had one of his last campaign rallies at Nashville's hippest nightclub, the Cabana. As he railed against Ford as a product of 'DC not Tennessee' jarring images appeared on TV screens above the marbletopped bar. CNN was running a special programme on events in Iraq but no-one in the room seemed to notice the carnage playing soundlessly just 20 feet from the platform.

In other parts of America, Republican campaign rhetoric buckled under the weight of anti-war sentiment but in Tennessee's conservative biosphere it proved more resilient.

Harold Ford came very closing to defeating Bob Corker but only by coopting the code of 'Red America'. A photograph in local papers showed Ford leaving the Little Rebel Bar and Grill in Jackson, Tennessee after a campaign event. The man who might have been the first black Senator from the South since reconstruction is pictured in a hunter's camouflage cap walking past a confederate flag painted on the wall of the bar.

Ford's defeat, and national exit polls, suggested that some parts of the Republican coalition remain in place, despite the party's humiliation last week. Seventy per cent of white evangelicals voted for Republican candidates and proposals to ban gay marriage were passed by big margins in Tennessee and Virginia. Yet the sacred union between evangelicals and the Republican Party seems increasingly loveless. In Virginia, 30% of those who backed the gay marriage ban also backed the Democratic candidate for Senate, James Webb. It is a small chink in a foundation block of Republican dominance but a potentially significant one.

Another big worry for Republicans is the decline in their vote among the most vibrant groups in American society. The party's support among Latinos was down 14% on the 2004 elections and more serious still is a collapse of support among voters with no formal affiliation to either party: those prized independents.

The results also suggest that Republicans risk losing their current advantage in the suburbs of America's most dynamic cities, particularly those in the South-West.

It's not just the scale of Republican losses that matter, but also the breadth of the gains made by Democrats. They mounted serious challenges in states like Wyoming and Idaho and won House seats in Kansas suggesting these elections could be more than just a passing protest against an embattled President. But is it too early to talk about the end of an era of Republican dominance?

The answer to that question partly depends on how Democrats rise to the challenge set for them by American voters. These elections delivered a bumper harvest for Democrats but also sowed the seeds of future divisions. If you had witnessed the campaign run by Democratic candidates in swing districts you would know why.

The 11th District of North Carolina is a good example. Nestled in the foothills of the Appalachians, this stronghold of 'Mountain Values' was served by a Republican congressman for 16 years and backed George Bush. Last week, the district elected Democrat Heath Shuler, a former Washington Redskins quarterback with a vice-like handshake and permanent smile. His campaign leaflets showed him in full hunting gear, with one arm cradling a shotgun and the other his pet Labrador. The flyer carried the logo of the National Rifle Association, a group that ranks up there with Dick Cheney on the liberals' enemies list. By way of explanation, Shuler told me: "I've always thought of the Democratic party as a broad tent."

Which begs the question: how broad can that tent get without splitting apart? How do Democrats reconcile the fact that Nancy Pelosi, a liberal from San Francisco, will be elected the first woman speaker of the House of Representatives with the help of conservatives who ran against the values she represents?

Outright civil war among Democrats is unlikely in the short-term.

Heath Shuler and Nancy Pelosi may differ radically on social issues, but on economics they use the same populist code, promising to defend 'working men and women' against 'special interests'. The new conservative Democrats also prize civility above all else: "Politics is all about relationships, " Shuler blandly told supporters.

But the relationship between left and right will be sorely tested as the Democratic Party tries to find a presidential candidate who convincingly speaks the languages of both Red and Blue America. Hillary Clinton has impressed people with her ability to straddle divisions in the US Senate (bonding with conservative Republicans at weekly prayer meetings while downing vodka shots with potential rival John McCain on a recent foreign trip). Still, there are accumulated passions swirling around Clinton that could well spook any Democratic politicians that are seeking re-election in 2008.

When they do find a candidate, Democrats will have issues which help them connect with the conservative heartland. Iraq is most definitely one such issue and so too are concerns about America's economic future. You even hear the language of social justice being spoken among white evangelicals.

Heath Shuler's campaign volunteers were advised to talk about global warming to religious voters:

'Revere God's garden' was the suggested catchphrase.

These elections may have been an endorsement of Democrats who speak the language of conservative values, but they also strengthened the hand of those seeking to push America to the left. Until someone emerges from that big, broad Democratic tent to resolve that contradiction, that code of 'them' and 'us' will retain a powerful hold over American political culture.

Prime Time presenter Mark Little reported for RTE News and Current Affairs on last week's mid-term elections in the US.